PREPARATION AND PROPERTIES OF ANTIGEN-60 FROM MYCOBACTERIUM-BOVIS BCG

  • 1 November 1986
    • journal article
    • research article
    • Vol. 66  (2) , 262-272
Abstract
Antigen 60 (A60) is the main thermostable immunogen of both ''old tuberculin'' (OT) and ''purified protein derivative'' (PPD), known reagents for cutaneous tests in tuberculosis. It is recognized by bidimensional immunoelectrophoresis with anti-BCG antiserum, where it appears as the less mobile component. A60 was prepared from the cytoplasm of Mycobacterium bovis BCG, and purified by exclusion gel chromatography and lectin affinity chromatography. Labelled A60 was obtained by radioiodination and used for a radioimmunoassay. Composition of A60 was explored by use of organic solvents, chemicals and enzymes. It contained two fractions of free and bound lipids, as well as protein and polysaccharide moieties. After removal of both free and bound lipid fractions, the core still retained the ability to form immunoprecipitinogen lines with anti-BCG anti-serum. The lipopolysaccharide and lipoprotein moeities of A60, as well as the free lipid fraction, were also complexed by antibodies. It is concluded that A60 is a lipopolysaccharide-protein complex of 106 to 107 daltons, which is a major immunogenic component of mycobacterial cytoplasm. The detailed structure of this antigen, its immunological properties, and its use for an ELISA type immunoassay for tuberculosis are described in two publications.

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